15-year-old had 'kill list' when he allegedly murdered teen

A US woman was murdered by a 15-year-old boy who listed her sister on his 'kill list', police say.

Makayla Grote, 19, from Boulder, Colorado was stabbed to death by the suspect, who has not been named, when she opened the door of their home around 6pm on November 18, reports local television station KDVR.

A 15-year-old boy has been arrested on first-degree murder charges on suspicion of killing 19-year-old woman Makayla Grote. Picture: Supplied

Once he had stabbed Ms Grote in the head and chest using a hunting knife, police say the killer chased her sister through the apartment, but the woman was able to lock herself in a bedroom, causing the accused to give up and leave.

The Denver Post reports Ms Grote was found by a neighbour and taken to Longmont United Hospital, but later died of her injuries.

After arresting the suspect, police searched his bedroom and found a list of names of people he intended to kill, with Grote's sister's name at the top, the Boulder County District Attorney's Office said.

The list apparently stated he would kill anyone in the home of his intended target.

Chillingly, when the teenager was found hiding in his parents car and arrested, he was less than two kilometres away from the third name on his list.

Ms Grote was an aspiring NASCAR driver. Picture: Supplied

Police allege the boy knocked on the Grotes' door around 11am that day asking for a jump start for his car. He then returned around 6pm to carry out his plan.

He was previously arrested for assaulting his grandfather, and when police searched the home he shared with his mother on that occasion they found molotov cocktails.

Ms Grote, who graduated from Green Mountain High in 2016, has been remembered as a warm and happy young woman who aspired to be a NASCAR driver.

Ms Grote was taken to hospital with stab wounds, and later died from her injuries. Picture: Supplied

She worked at Colorado National Speedway, and on a GoFundMe page started by her colleagues to pay for her funeral expenses, Ms Grote was described as a beloved member of the racing community.

"A lot of us will remember that laugh and that smile she always had on her face."

The suspect was arrested on suspicion of first-degree murder and will be arraigned this week.